Improvement in pyrometers



ilttrd time EDWARD BROWN, `OF PHILADELPHIA, PENNSYLVANIA.

Leners Parent No. 102,654, lated May 3, 1870.

IMPROVIEMENT IN PYRoMETE-R-S.

The Schedule referred to in these Letters Patent and making part of the same I, EDWARD BROWN', 'of Philadelphia, aud State of Pennsylvania, have invented certain Improvements lin Pyrometers, 4of' which the following is a speciication.

The nature of my invent-ion consists in the mode of adjusting the pointer to compensate for inaccuracy, and also in the combination and arrangement of `the expansion tube with certain interior bars of highlyrefractory and small expansive qualities.

The details-of its construction I will now describe.

Figure 1 is a section through the instrument.

Figure 2 is a plan of the frame, showing elongated screw holes.

Figure 3 shows .the pyrometer in position in the hot-blast pipe.

Figure 4 shows the stem, with the protect-ingr tube attached.

The c'ase containing the movements is shown at A. It contains a frame, B, carrying segment C, and pinion D, to which the pointer is attached.

An arm, E, is adjusted by means of' a set-screw to the exact leverage corresponding with the expansion of the stem. To this arm is jointed the rod G, passa ing downward into the stem N. 'l Its length may be varied slightly by the pointed screw g.Y

W is an'adjustingscrew. One end is screwed into the case by a coarse screw; the'other into the frame B by a thread half as coarse.

The frameB is screwed tothe case A, not rigidly, but so as to permit of a motion endwise. The screw-` holes are slotted to suit, as shown atcb', iig. 2.

The head A is attached to the iron stem N by the coupling H, the upper thread being of a liner pitch than thelower one. A set-screw, h', may be inserted to secure the coupling from turning.

:The tube N is welded fiat across at its lower end. It is from twenty inches to three feet long in practice, and has a collar, M, secured by a set-screw about nine inches .from the top, to regulate the depth to insert the stem in the hot blast. Withiuthe stem, and resting on lthe bottom, is a, bar of black lead similar to that used for black-lead crucibles, a good proportion of whichis three-fourths plumbago and one-fourth Stourbridge clay.v Resting upon this is a bar or tube of porcelain, made outofA the best fire-clay. The ends are groundsquare, and the upper end is capped with-brass, into which passes the point g.

The bars are kept in contact,l and all the lost motion in the joints is taken up by the spring S.

It is obvious that the porcelain tube may be dis# pensed with, and the'cap K rest directly on the blacklead bar O. A

In iig. 4, P is an exterior protecting tube, screwedA to the collar M by ascrew, p. It is welded solid at'I the bottom, and entirely protects the stem from injury by deleterious gas or acid. f

The operation of the instrument IWill now describe. The tube N is inserted and secured in the hot blast up to the collar M. Within the tube, and restingon the bottom, isa bar of black-lead ware, O. This material is `very refractory, and permits of va pyrometer for high temperatures being made with avery short stem. I make no claim tothe use of black-leadlware of itself, as that was used for scientic experiments many years ago, but has never been so arranged and combined as to be practically useful in the arts.v 'lhe expansion of the metal stem N gives motion to the pointer of the dial through the gearing previously described. V

It has been' maintained by metallurgiststhat the metal stem permanently elon'gates under a continuous temperature of 7000 or 800. VSuch has been found to be the case with ordinarypyrometers, constructed with brass and iron combined stems. One of the features of my invention is to neutralize this, by constructingthe interior bar or bars of about equal lengthsv of black lead and fire-clay, whereby the instrument maintains greater' accuracy than when constructed of either alone. I have had one of these instruments in melted zinc at 850 for three months, and on taking it out the pointer returned to exactly the atmospheric temperaturefa result heretofore un` attainable. No pyrometersat' present in use have any means of adjustment of the pointer other than that of screwing .the head upon the stem-a very inconvenient pian, as the dial is thus turned out of sight, and can only be remedied by breaking the cemented joint of the stem, involving more trouble and expense, inv some cases, than the instrument is worth.

'To' provide against any inaccuracy vwhich may occur from long use, I have designed an' easy method of adjustment by 'the screw W. By simply turning itr upon the exterior of the case by a screw-driver, the

. frame B, with the segment and pinion, is moved bodily across the back ot the case, whilethe point of the spring pin g remains stationary within the stem N. In this way the pointer isadjusted at'any required point. Thus, should the porcelaintube be fractured by thc heat, the pointer 'may be adjusted, and still the instrument' be of service. Even inferior instruments of brass and iron, with this device, may be from time to time adjusted'by means of my detachable in` struments, patented' `June 1, 1869, and prove useful.

The instrument maybe adjusted by the screws upon the coupling H, but thatis very inconrenient.' Other means of moving the frame B relatively t-o the case A will easily' suggest themselves to a machinist, as an eccentric working through the back of the case.

When the instrument is used in situations where the action of the gas or acid will eat up a stem onequarter of au inch thick in three or four months, I protect it 'with a tight case, P, screwed to the collar M. As soon as this tube is eaten through, I replace it by another, and the pyrom'eter stem thus maintains its original perfection.

These improvements render an instrument practically useful which has heretofore been so shortlived 'at temperatures above ZOOo as to be regarded with distrust by iron-masters.

What I claim as my inventon,and desire to secure by Letters Patent, is-

1. The arrangement ofthe black-lead bar O within the metal-expansion and protecting tube N, andA oplent, operating the frame B, as described, in combination with the pinion D, segment C, and spring pin G, for adjusting 'the pointer substantially as herein set forth.

EDWD. BROWN Witnesses PARK MGFARLAND,

Jos. BABY. 

